1. Field of the Invention
This invention relates, generally, to an integrated snorkel and diving regulator for use while snorkeling near a water surface and while diving under water. It also relates to structure for reducing the pressure of a high-pressure gas to a breathable pressure.
2. Description of the Prior Art
SCUBA (Self-Contained Underwater Breathing Apparatus) divers typically use a conventional snorkel to preserve air from the SCUBA air supply pressurized tank when swimming on or near the surface, i.e., at snorkeling depth, and viewing under water. When a diver decides to dive below the water surface, the diver removes the snorkel tube mouthpiece, clears the SCUBA diving regulator with a blast of air from the pressurized tank, and commences breathing through the mouthpiece of the SCUBA diving regulator so that the diver can continue breathing pressure-regulated air from the tank while submerged.
There are several patents disclosing products on separate diving snorkels and diving regulators. None of these products have successfully integrated a snorkel with a diving regulator, enabling a diver to seamlessly transition from breathing atmospheric air when swimming at snorkeling depth to breathing pressure-regulated air from a tank when submerged.
Thus there is a need for an integrated diving snorkel/regulator that combines the operation of a snorkel with that of a diving regulator, enabling snorkeling and underwater diving using a single apparatus.
A conventional snorkel has a tubular main body. A mouthpiece is secured to a first or proximal end of the tubular main body and a valve is mounted to a second or distal end of the tubular main body. When the swimmer submerges, the valve closes, prohibiting water from entering the tubular main body. No air is supplied to the snorkeler during such submersion.
A conventional SCUBA diving regulator enables a diver to breathe air supplied from a pressurized tank strapped to the diver's back. Pressure regulators perform the function of reducing the air pressure in the tank, usually in two stages, before it reaches the diver. The first stage is typically located at the SCUBA diving tank, and reduces the tank pressure to an intermediate pressure.
The second (demand) stage supplies air when the diver inhales and exhausts air when the diver exhales. The demand stage usually includes a mouthpiece, a piston or diaphragm that senses when the diver inhales, a breathing chamber that fills with air, an exhaust valve that vents exhaled air to the water, and a sensitivity adjustment means by which the diver can adjust the air flow from the first stage regulator. A conventional sensitivity adjustment means includes an elongate valve having a valve seat, a rocker arm, and a spring. A valve seat is seated in a volcano orifice when the first stage is closed.
Conceptually, a conventional diving regulator employs a simple lever and fulcrum system as depicted in FIG. 1 (Prior Art).
Under normal operating conditions, air pressure within the breathing chamber of a diving regulator balances the water pressure acting on the outside of diaphragm 12. External water pressure acting on diaphragm 12 is indicated by directional arrows 12a and the air pressure inside the mouthpiece is indicated by directional arrows 12b. 
Diaphragm 12 and valve spring 14 are connected to one another by lever 13 which pivots about fulcrum 13a when the competing pressures represented by directional arrows 12a and 12b are not in balance. FIG. 1 depicts the equilibrium position of lever 13 when said pressures are balanced.
The bias of regulator valve spring 14 provides a closing force indicated by directional arrow 16 that is applied to regulator valve 18 to contain tank pressure indicated by directional arrow 20 and to ensure that regulator valve 18 remains closed under slight variations of water or tank pressure. Regulator valve 18 is in fluid communication with tank pressure 20 through air inlet hose 22. Regulator valve 18 is closed as depicted when lever 13 is in its position of equilibrium or repose.
Typically, the compressed air tank provides a pressure of one hundred twenty to one hundred fifty pounds per square inch (120-150 psi), and the area of regulator valve 18 is about three-hundredths square inches (0.03 in2). This requires a valve spring bias force 16 of about four to five pounds (4-5 lbs).
As depicted in FIG. 2 (Prior Art), when a diver submerges, external water pressure 12a increases, causing lever 13 to pivot about fulcrum 13a, thereby overcoming the bias 16 of valve spring 14 and enabling the opening of regulator valve 18. When regulator valve 18 opens, air 20 from the diving tank enters into the breathing chamber, not depicted in FIG. 2. This equalizes pressures 12a and 12b. Lever 13 returns to its FIG. 1 position of repose and regulator valve 18 returns to its closed position under bias 16 of valve spring 14.
A similar situation occurs when the diver breathes from the diving regulator mouthpiece. The air pressure within the breathing chamber is reduced by an inhalation, causing lever 13 to pivot about fulcrum 13a, opening regulator valve 18. This allows air from the compressed air tank to fill the breathing chamber, pass through the mouthpiece and enter into the diver's lungs. When the diver has finished taking a breath, air 20 from the tank once again causes pressure 12b within the breathing chamber to balance or equalize with external water pressure 12a. 
The interconnection of a conventional snorkel to a conventional diving regulator results in an imbalance between water pressure 12a with air pressure 12b within the breathing chamber of the diving regulator. When the diver is on or near the surface of the water, i.e., swimming at snorkeling depth, the distal end of the snorkel is in open fluid communication with the atmosphere. Therefore, the air pressure within the diving regulator breathing chamber is also at atmospheric pressure, i.e., nominally 14.7 psi). The pressure of the water, however, increases at a rate of thirty six hundredths pounds per square inch per inch (0.036 psi per inch) of depth. At typical snorkeling depths of eight to twelve inches (8-12″), water pressure 12a acting on the outside of diaphragm 12 is about fifteen and one-tenth pounds per square inch (15.1 psi), resulting in a pressure differential relative to atmospheric pressure of about four-tenths of a pound per square inch (0.4 psi).
An imbalance between said water pressure 12a with air pressure 12b within the breathing chamber causes lever 13 to pivot about fulcrum 13a and to open regulator valve 18, causing air to flow from the diving tank into the breathing chamber as aforesaid. However, due to its open fluid communication with the snorkel, the distal end of which is not submerged, the diving regulator breathing chamber is open to the atmosphere and air pressures 12a and 12b cannot balance one another. This is known as a free flow condition, i.e., regulator valve 18 does not close and air 20 from the diving tank continues to vent to the atmosphere.
For this reason, the known combinations of snorkels and diving regulators waste the air in the SCUBA tank during snorkeling.
It would be desirable to combine the functions performed by a snorkel and a SCUBA diving regulator. However, these are two separate structures and the solution to the free flow condition was not obvious to those of ordinary skill, in view of the prior art as a whole, at the time the invention was made.